What it means
までに marks a deadline or a point that must be reached no later than a specified time. It can follow a time expression, such as 三時 or 金曜日, and it can also follow a verb in the dictionary form when meaning “before or by the time that an action happens.” The action described with までに is completed by that time, while the main action may happen earlier or exactly at the deadline.
Usage note
Do not confuse までに with まで. までに marks a deadline, whereas まで usually means that an action or state continues until a particular time or point.
How to use it
会議は三時までに終わります。
The meeting will end by three o'clock.
私は日本へ行くまでに、ひらがなを覚えたいです。
I want to learn hiragana before I go to Japan.
会議は三時までに終わる。
The meeting will end by three o'clock.
私は日本へ行くまでに、ひらがなを覚えたい。
I want to learn hiragana before I go to Japan.
Example sentences
図書館の本は、来週の月曜日までに返してください。
Please return the library books by next Monday.
申込書は今月末までに郵送してください。
Please mail the application form by the end of this month.
先生にレポートを金曜日までに提出します。
I will submit the report to the teacher by Friday.
出発するまでに、駅で